1. Technical field
The invention relates to the handling of container bodies and in particular to a method and an apparatus for separating a series of container bodies, and methods and apparatus for bringing container bodies together.
2. Background Information
As is known, container bodies, and in particular can bodies, are transported on conveyor belts with the body lying, or suspended in the prone position, and subsequently have to be turned through 90xc2x0 for further processing, so that the can body is carried onwards in the upright position. FIG. 1 shows, highly schematically, an apparatus for carrying out this maneuver. A series of can bodies 2, of which only four are shown are transported on a first conveyor belt 1, at a speed V1, and with a gap of approximately 3 to 4 mm between the can bodies. At this stage the can bodies are held on the conveyor belt e.g. by permanent magnets. The can bodies are to pass on to a further conveyor belt 4 on which they are stood upright in order to undergo further processing in a known manner. The can bodies cannot be transferred directly from the conveyor belt I to the conveyor belt 4, as the gap between the can bodies is so small that this would result in collision between successive can bodies. Another conveyor belt 3 is therefore interposed between the conveyor belt 1 and the belt 4, and is run at a speed V2 which is higher than the speed V1. This results in an increased gap between the can bodies on the belt 3, as the figure shows. Each can body 2 arriving at the conveyor belt 4 is then at a sufficient distance from the next ran body to allow it to be picked up and conveyed away by the conveyor belt 4 before the next body lands on the belt 4. The arrangement in FIG. 1 is highly schematic, and is shown without the known means for fixing the can bodies; e.g. to the belt 4. The can bodies are held on the conveyor belts 1 and 3 preferably by magnetic force, as has already been mentioned, and as is also known.
Because machines used for the fabrication of can bodies, especially roller seam welding machines, are capable of operating at ever-increasing speeds, the problem arises that the speed V1 is already very high. For example it may be that 1000 bodies per minute are being transported on the conveyor belt 1, which means that the conveyor belt has to be travelling at high speed. Because the speed V2 of the belt 3 must be higher than the speed V1 in order to increase the gap between the can bodies, the resulting speed V2 is so high that transfer to the conveyor belt 4 becomes problematic, as the can bodies impinge on the conveyor belt 4 at high speed. U.S. Pat. No. 5,423,410 proposes, as a way of solving the problem, that the stream of cans be separated into two streams, using two parallel conveyor belts lying in the same plane. A transfer device pushes individual can bodies from one belt on to the other parallel belt. The can body has to traverse a relatively large distance in making this transfer, and the transfer from one belt to the other is made abruptly, which may cause damage to the body. On the one hand there is therefore the aim of providing a method and/or an apparatus whereby can bodies, even if conveyed at a rapid rate, can be divided between two or more belts, without any problem, and in the gentlest possible manner, for further processing.
Furthermore, some of the can bodies transported at a rapid rate on the conveyor belt 1 may need to be removed from the conveyor belt because they have been identified as defective by a quality control system. These bodies must not be sent on for further processing. A known solution is to eject such bodies from the conveyor belt 1; e.g., by a jet of air. The result is that the ejected body leaves the belt at high speed, in an uncontrolled manner. If for example, ejection takes place before the inner coating of the can body has dried, this ejection from the conveyor line causes coating powder or coating lacquer to be dispersed over the surrounding area, which is undesirable. Therefore, there is the further problem of providing a method and an apparatus by means of which individual can bodies may be removed, in a controlled manner, and in the gentlest possible way, from the series of can bodies being transported on a conveyor belt 1. GB-A 2114083 discloses a can body switch in which the stream of bodies is divided at a break-point of the conveyor belt by means of electromagnets arranged on either side. This arrangement is expensive, and at high rates of transfer may lead to malfunctions due to the absence of a positive grip and to high centrifugal forces.
The problems stated can be solved using a method and/or an apparatus in which a second conveyor is operated at substantially the same speed as a first conveyor carrying a series of can bodies, and is made to pass close to the first conveyor means along a section of conveyor path and then diverges therefrom, such that the conveying plane of one conveyor means does not coincide with the conveying plane of the other conveyor means at least in the said section of conveyor path. By means of a controllable application of force, individual bodies are transferred from the first conveyor means to the second conveyor means, on which the bodies are held and are successively removed from the series by the divergence of the path of the second conveyor means from the first conveyor means. The first conveyor means is formed by a first conveyor belt extending in a straight line in the region of separation, and is characterized in that the bodies are held on the first conveyor belt by permanent magnets or mechanically. The second conveyor is formed by a second conveyor belt behind which a plurality of electromagnets or permanent magnets are arranged one after the other in the conveying direction. The electromagnets are actuated by a control unit so that the force tending to hold the bodies on the first conveyor belt is overcome or so that the bodies are transferred to the permanent magnets of the second conveyor belt by controlled application of mechanical force so that the holding force of the first conveyor belt is overcome. Thereby individual bodies are caused to be transferred to the second conveyor belt.
The problems can be solved by providing the second conveyor means which initially extends close to the first conveyor means but in a different plane and is able to accept can bodies from the first conveyor means. The second conveyor means may thereby contact or almost contact the can bodies to be transferred, so that practically no displacement of the bodies by application of force is necessary, and the bodies are gently removed in succession from their original series through the divergence of the second conveyor means.
On the one hand, a stream of, e.g., 1000 container bodies per minute can be divided into two streams of 500 container bodies per minute in this way, and each of these two streams can be fed separately to a conveyor belt for standing the can bodies upright. This eliminates the need for a transfer belt 3 travelling at increased speed. On the other hand, the method and/or apparatus according to the invention can be used for removing particular bodies from a series of container bodies in a controlled manner so that there is no risk of bodies flying about or of contamination with coating powder or coating lacquer when removal occurs.
The reverse function may also be desired, say a single stream of bodies is to be formed from a number of such streams. This problem is solved by the method and apparatus in which one conveyor means carrying one stream of container of bodies is made to pass close to another conveyor means carrying another stream of container bodies along a section of conveyor path, such that the conveying plane of one conveyor means does not coincide with the conveying plane of the other conveyor means at least in the said section of conveyor path. By means of a controllable application of force individual bodies are transferred from one conveyor means to the other conveyor means, on which these bodies are held. One conveyor means is formed by a conveyor belt. The bodies are held on one conveyor means by permanent magnets and the other conveyor means is formed by a second conveyor belt behind which a plurality of electromagnets are arranged. The electromagnets are actuated by a control unit so that the holding force of the permanent magnets is overcome, causing the bodies to be transferred to the second conveyor belt. This solution is based on the same principle as that proposed for dividing a stream.
The object can also be achieved by a methadone apparatus in which the bodies are guided on to a single belt-form conveyor means provided with controllable V-shaped holding devices for the bodies, the holding devices being divergent for separating the bodies or convergent for bringing the bodies together and controlled so that the bodies are separated or brought together as the case may be. The holding devices are formed by magnetic holding means arranged underneath the conveyor means.